Malaysia’s opposition leader today said he had enough parliamentary support to topple the government and urged the prime minister to give up power peacefully.

Anwar Ibrahim, who has set today as the deadline for taking power, refused to spell out what his majority would be in the 222-member assembly, but he needs 30 government MPs to defect and join his coalition of 82 members.

Political tension has been high in the run-up to today’s deadline, as the government used its Internal Security Act (ISA) to arrest a leading political blogger, a journalist and an opposition politician.

Anwar told supporters at a rally yesterday that he was willing to give the prime minister, Abdullah Ahmad Badawi, one or two weeks to accept defeat and resign.

But “there is a limit to one’s patience, particularly when we have the numbers”, Anwar said today. He warned the government not to invoke security laws to arrest defecting MPs.

“We are firm that victory is finally at hand. Our vision of rebuilding this country … is within reach,” he said.

Abdullah brushed off Anwar’s claims of having won over enough government MPs. “This is Anwar’s mirage. It is nothing. It is merely a dream,” he said.

The government has been on the back foot after losing its two-thirds parliamentary majority in March for the first time since independence over 50 years ago.

Anwar said that if he formed the next government, he would root out corruption and end a system of affirmative action for ethnic Malays, more than half of the 27 million population.

The opposition says the system has failed the people it was aimed at helping and created a class of crony businessmen dependent on the government.

Anwar leading a new government would be a remarkable comeback. He was the anointed successor to Malaysia’s long-serving leader, Mahathir Mohamad, until the two fell out. Anwar was sacked and imprisoned on a sodomy conviction in 1998. The conviction was overturned in 2004 after he had served six years in jail for a related corruption conviction.

Over the last year, Anwar has cobbled together a coalition of three diverse political parties, including his multiracial People’s Justice party, ahead of the pivotal March 8 general elections.

Anwar was charged this year with raping a young male aide. He has dismissed both accusations as politically motivated to stop his comeback. No date has been set for his trial.

The ruling National Front coalition has been weakened by dissent against Abdullah, who has seen his authority erode rapidly since the March vote.

The political uncertainty has hit business and market confidence in one of south-east Asia’s most stable countries. — Guardian